Timing apparatus



Sept. 1, 1936. o. c. FREDERICK TIMING APPARATUS Filed July 22, 1933Invefitor: Oscar C. Frederick,

[*atented Sept. 1, 1936 UNITED STATES PATENT OFFICE 2,053,143 TIMINGAPPARATUS v New York Application July 22, 1933, Serial No. 681,700

6 Claims.

My invention relates to apparatus for timing industrial operations whichmust be repeatedly performed in a predetermined interval of time.

My invention is particularly suited for timing resistance weldingoperations such as are encountered in spot welding or flash weldin Accurate time control of the welding current, particularly for such metalsas stainless steel, aluminum and the like, is highly important. It be-10 comes more essential with these metals than ordinary steels. It hasbeen found that it is necessary to have the time extremely short and thecurrent values relatively high. This is especially necessary in thewelding of stainless steel, as it 315 prevents the combination of carbonand chromium which destroys the stainless qualities of the steel andpermits corrosion.

It is an object of my invention to provide an im proved apparatus foraccurately timing a welding operation independently of the operator whois free to initiate the operation but cannot thereafter interrupt ituntil a predetermined welding time has elapsed.

it is a further object of my invention to provide apparatus of thecharacter described which will be small in size and cheap enough towarrant its use with small sized equipments such as are used forperforming certain spot welding or stud welding operations. 7

Further objects of my invention will become apparent from aconsideration of the following description of one embodiment thereofwhich has been diagrammatically illustrated in Fig. l of i theaccompanying drawing and a modification as thereof shown in Fig. 2 ofthis drawing,

in this drawing the circuit to be controlled i, extends from a sourcealternating current surply 3, i to the primary of a welding transformert. This circuit is completed by an electromagnetlc switch l whoseoperating coil 2 is connected to the source or" supply l through thefollowing circuit: From supply conductor through con ductor 9, controlswitch it, which is normally biased to an open position, conductor ll,con= l5 ductor l2, switch iii of a timing relay i conductor 35, safetyswitch l8, and a conductor ii to supply conductor l. When theelectromagnetic switch closes, an auxiliary switch in shunt to thecontrol switch ill is also closed completing a holding iii? circuit forthe electromagnetic switch through the following circuit: From supplyconductor through conductor is, auxiliary switch it, conductor l2,switch ill of timing relay it, conductor l5, safety switch It andconductor ill to supply conductor 4. The safety switch it may be ahand-operated switch which is latched in the closed position untilopened. upon an overload through the agency of its tripping coil 20.This switch is provided to protect the control circuits which may bedamaged by the flow of abnormal 5 currents therein such as might occurupon the short circuiting of exposed conductors by a careless operatorwhile adjusting the timing relay.

The movable contact of switch 13 is normally biased into engagement withthe fixed contact of 10 the switch by means of an operating member 2|.The end of this operating member extends between and in the path ofmovement of arms 22 and 253 of the timing relay M. The arm 22 ispermanently fixed to the shaft 2d of the relay and the arm 23 isadjustahly supported thereon and held in adjusted position relative tothe arm 22 by means 0; a clamping nut 25. Arm 22 is pro vided with adial plate upon the surface of which there are graduations by means ofwhich 20 the adjustment of the arms 22 and 23 may be facilitated. Themovement of the operating member 25 is limited by adjusting screws 2iand 22 which through the agency oi the operating member 2t constitutestops for the arms 22 and The ad 25 justing screw 22 also supports thefixed contact of the switch l3.

Forward and reverse rotation is imparted to the arms 22 and 23 of relayi by means of self-start ing synchronous motors 29 and forming U or" therelay. Ihese motors maybe oi"; the con struction more fully illustratedand desricecl in United States Letters Patent No. 5 Warren, July 14,1925. They are pole faces of motor 29 are counterclockwise or forwardrotation 22 and whereas the shading coils pole faces of the motor arearranged t a clockwise or backward rotation of hes means of which thcommon to the shaft upon which the a are supported. It is to he notedthat the rotors of these motors are permanently connected arm 22. Thearrangement of rotating on closed within the casing and lid he such asillustrated in United States Le ters No. 1,459,936, H. E. Warren,granted May 27, 192 5. For timing operations of short duration thegearing is suitable to impart a complete rotation to arms 22 and 23 in.one second of time. a

- plate 26 of arm 22 may then be marked to indicate timing periods incycles.

Motor 29 being a synchronous motor inherently operates in step with thefrequency of the source of supply 3, 4 and the arm 22 is preferablyfixed on the shaft 24 so as to break the operating circuit of theelectromagnet switch 'I at switch i3 at the proper time to cause theelectromagnetic switch I to open at the zero or on the declining part ofthe voltage wave of the source of supply. This greatly relieves the dutyon the contacts of the electromagnetic switch and facilitatestheoperation of the control apparatus. This adjustment will, of course,depend on the characteristics of the switch used in the control circuit.I have successfully employed an electromagnetic switch having theconstruction disclosed and claimed in the application of Ludwig S.Walle, Serial No. 667,856, filed April 25, 1933, and assigned to thesame assignee as the present application. In such a switch the contactsare sealed within a closed chamber and the arc drawn-between theseparating contacts generates a gas pressure within the chamber whichrapidly increases and quickly extinguishes the arc. When using a switchof this description to interrupt the circuit of 10 and 25 Kva.transformers, I have found that it is necessary to open the circuitthrough switch I3 at approximately the peak of the voltage wave foroscillographs indicate that the operation of the pressure switch lagsthe operation of switch i3 by approximately a quarter of a cycle. Withthis adjustment the pressure switch opens the welding circuit on thedeclining part of the voltage wave.

The field coil 35 of motor 29 is initially connected to the source ofsupply 3, 4 through the following circuit: From supply conductor 3,conductor 9, control switch It, conductors 31, 38, 39,,

tor l9, auxiliary switch l8 of electromagnetic switch I, conductors ll,31, 38, 39 and i5, safety switch It and conductor H to the source ofsupply 4. It is to be noted that motor 30 is normally energized and isonly deenergized during the operation of timing motor 29.

The field coil 36 of motor 30 is connected to the source of supply 3, 4through the following circuit: From supplyconductor 3 through conductors9 and 40, contacts 4| of relay 42, conductors 43, 44, 39 and I5, safetyswitch It and conductor I! to supply conductor 4. When relay 42 isenergized this circuit is interrupted at contacts 4|. The operating coil45 of relay 42 isinitially connected to the source of supply 3, 4through the following circuit: From supply conductor 3 through conductor9, control switch It], conductors 31 and 46, safety switch l6 andconductor I! to the .to the source of supply 3, 4 through the followingcircuit: From supply conductor 3 through con- 'ductor l9, auxiliaryswitch I8 of the electromagelectromagnetic switch 1 and energizes theselfstarting synchronous motor 29 and simultaneously deenergizes theself-starting synchronous motor 30 through the agency of relay 42. Assoon as the electromagnetic switch closes the auxiliary switch |8associated therewith is also closed.

This switch is connected in shunt to the control.

switch i6 which is normally biased to an open position and opens as soonas the operator releases it. Once started the welding operation willcontinue until the arm 22 of the timing relay i 4 engages the switchoperating member 2| and opens switch IS in the operating circuit of theelectromagnetic switch I. The opening of switch l3 deenergizes theelectromagnet 8 of this switch as well as motor 29 and relay 42. Thedeenergization of relay 42 connects the motor 30 to the source of supply3, 4 as pointed out above and this motor will then return the parts totheir initial positions illustrated in the drawing. These positions willbe determined by the adjustment of set screw 28 which in conjunctionwith the switch operating member 2| constitutes a stop for the backwardmovement of arm 23 which on stopping stalls the normally energized motor30. The set screw 21 in conjunction with the operating member 2| of theswitch |3 constitutes a stop for the forward movement of arm 22. Theprovision of such a stop'is not necessary but is effective in preventingforward travel of the arms 22 after the motor 29 has been deenergized.This shortens the time required by motor 30 to reset the timing relay.Set screw 21 may in some applications of my timing relay support a fixedcontact which is suitably connected in the control circuit.

It will be noted that once the welding operation has been initiated bythe operator closing the control switch ill, the duration of the weldingoperation is no longer under his control, but is determined by theoperation of the timing relay I4. However, unless the operator releasesthe switch I!) so that it may be returned to its normal open position,the timing relay M will not reset itself due to the disconnection ofmotor 30 from the source of supply 3, 4 at contacts 4| of relay 42 whichis maintained energized so long as control switch Ill is held in itsclosed position.

With a timing relay of the construction illustrated in Fig. 1, it ispossible for the operator toobtain a faulty timing operation if thecontrol button Ill is closed before the resetting motor 30 has had anopportunity to fully reset the relay. This result will follow by reasonof the fact that if the control button is depressed the system will beset into operation soon as the contacts of the timing relay are closed,and these contacts will be closed as soon as the arm 22 of the relaywhich has openedthem has been moved in a resetting direction a veryshort distance. By modifying the construction of the relay M asillustrated, in Fig. 2 of the drawing, this possibility of faultyoperation of the system may be completely avoided. By referring to thisfigure it will be noted that the operating member 2| of the switch I3 ispivotally supported at "and provided with a toggle 48 by means of whichit is held in engagement with the set screw 26 until arm 22 forcefullymoves it therefrom and in engagement with set screw 21 until arm 23forcefully moves it from engagement therewith. This toggle comprises anotched plunger 49 inserted in a support 56 and provided with a spring5| inserted between the head of the plunger and the support 50. Thenotch in the plunger furnishes a bearing for in ele the pointed end 52of the operating member 2|. With a construction such as illustrated inFig. 2 it will be noted that the operating circuit through switch illwill not be completed until the operating member 2| for the switch hasbeen moved to the position illustrated by a backward movement of the arm23. It will thus not be possible for the operator to initiate anoperation until the timing relay has been fully reset and, consequently,the timing operation will be of a predetermined duration irrespective ofthe activity of the operator.

The welding time is determined by the relative adjustment of the arms 22and 23. Depending upon the gear reduction employed in the trans-.mission between'the arms 22 and 23 and the motors 29 and 30 the durationof the weldingperiod may be greatly varied. In one embodiment of myinvention in which the arms 22 and 23 are given one complete revolutionin one second, timing operations from 2 to cycles have been obtainedwith a cycle source of supply by suitably adjusting the arms 22 and 23relatively to one another. Oscillographic records have proved that thetiming period once established may be repeated with very little error.The contacts of the switch l3 should be made of some wear-resistingmaterial so that repeated opera tion of the switch i3 will not changethe duration of the timing period once the apparatus has been set.

7 It is apparent that the switch operating mem her 2! may be the controlelement of any device which it is desired to operate after the lapse ofa predetermined period of time. It is also apparent that other meansthan the arm 23 in conjunction with the switch operating member it maybe used for limiting the resetting movement of arm 22. Thus, while Ihave described but one embodiment of my invention, it is to beunderstood that other embodiments thereof rnay be made without departingfrom my invention.

What 1 claim as new and'desire to secu-e by Letters Patent of the UnitedStates is:

l. Apparatus comprising a movable arm, a control element located in thepath of movement of said arm, a self-starting synchronous motorconnectedto move said arn'i into engagement with said control element, asecond normally energized motor connected to move said arin away fromsaid control element, means for stalling said sec-- ond normallyenergized motor after a predetermined separation of said arm from saidcontrol element, source oi alternating current, and means tordeenergizing said second motor and for connecting said first-mentionedmotor to said source alternating current until arm open ates saidcontrol element.

2. Apparatus comprising a plurality oi arms, a on which said arms aresupported, means or adjusting the separation of said arms, timing p cansfor rotating said sha t in one direction at 3 will! a re eterzninedspeed, reset g means operative said timing means is inoperative forrotatg said the reverse direction, a control ment located between and inthe path of mo /e rnent of said arms, stops on each side said controlelement which limit the movement therewhen actuated by said arms, meansfor initiating the operation of said timing means, and means operated bymovement of said control element for interrupting the operation of saidtiming means.

3. Apparatus comprising a plurality oi arms, a shaft on which said armsare supported, means for adjusting the separation of said arms, timingmeans for rotating said shaft in one direction at a predetermined speed,resetting means operative when said timing means is inoperative forrotating said shaft in a reverse direction, a switch 5 biased to eitherone of two positions and having an operating member located between andin the path of movement of said arms, means including said switch forinitiating the operation of said timing means after said switch has beenmoved to one of said positions by said resetting means, and meansincluding said switch for interrupting the operation of said timingmeans when said switch is moved from said one position to said otherposition.

4. Apparatus comprising a plurality of arms, a control element locatedbetween and in the path of movement of said arms, means for adjustingthe separation of said arms, timing means for imparting a forwardmovement to said arms, resetting means operative when said timing meansis inoperative for imparting a backward movement to said arms, means forstalling said resetting means and limiting the backward movement of saidcontrol element and said arms, means for simultaneously rendering saidtiming means operative and said resetting means inoperative, and meansresponsive to the forward movement of said control element for renderingsaid timing means inoperative and said resetting means operative.

5. Apparatus comprising a plurality of arms, a switch having anoperating member located between and in the path or" movement of saidarms, the backward movement of said member being limited by said switchin its closed position, means for adjusting the separation of said arms,a self-starting synchronous motor connected to impart a forward movementto said arms, a second normally energized self-starting synchronousrnotor connected to impart a backward movement to said arms until one ofsaid arms engages and is brought to rest by said operating member ofsaid switch, a source of alternating current supply, and means includingsaid switch in its closed position for connecting said first-=mentionedmotor to and for discon-= nesting said second motor from said source ofsupply until the other of said arms on its forwa d movement opens saidswitch by engaging its saio. operating member.

Appar oompris'ng a plurality of arms, a 5i Itch having an operatmgmember located be" ven in the path of movement of said arms, th wardinovern said member being ts ts closed position, means r supported,self-start to rotate said '1 lard direction, a sec normally energizedself-starting synchrono arms engages operating m alternating cu trolled,means switcli for co hiding electromagnetic lg said circuit to and fordis rcuit from said source of supply,

a starting swit ing post ,on, an auxiliary switch connected in shunt tosaid starting switch and closed and opened by the olosing'and opening ofsaid electromagnetic switch, means including said starting member anddeenergizes and opens said electromagnetic switch, and means includingsaid starting switch and said auxiliary switch for connect in: saidfirst-mentioned motor to and for dis- 1 connecting said second-mentionedmotor from said source of supply.

OSCAR C. FREDERICK.

